Palos Verdes Shelf Superfund Site Fact Sheet
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Palos Verdes Shelf Superfund Site U.S. ENVIRONMENTA L P ROTECTION A GENCY $ REGION 9 $ S AN FRANCISCO, CA $ F EBRUA RY 2008 Remedial Investigation Report Completed; Feasibility Study Underway The Palos Verdes Shelf Superfund site is an area of con taminated sediment off the Palos Verdes Peninsula. The contaminated sediment lies in the Pacific Ocean at depths of 150 ft. and more, too deep for human contact. However, the fish found in the Palos Verdes Shelf area contain high con centrations of DDT and PCBs. Although current concentra tions have dropped from historical highs, concentrations of DDT and Remedial PCBs in fish continue to pose a threat to human health and the natu ral environment. Investigation Report At-A-Glance 118 30’ 118 20’ The Remedial Investigation (RI) summa Santa Monica Bay rizes: 33 50’ LOS ANGELES COUNTY $ the nature and extent of contamination, 100 Redondo Canyon $ the transport and fate of the 50 90 20 80 contamination 100 Palos Verdes 200 Palos Verdes Peninsula 70 Point $ current risk to human health and the 300 400 500 environment from the site. 600 Portuguese Bend Landslide 700 Pt. Vicente Although discharge of DDT and PCBs Los Angeles Harbor stopped over 30 years ago, these persistent shelf pollutants remain in the sediment off Palos White Point slope Pt. Fermin Verdes Peninsula. The RI found the quantity shelf LACSD outfalls 20 of DDT and PCBs has dropped over the 800 slope 50 years. Some of the contaminants have been Palos Verdes shelf break Shelf Site carried off the shelf into deeper waters, some 33 40’ have been diluted by mixing with cleaner sediment, and within the contaminated sedi ment deposit we found evidence that DDT— North 0 2.5 5 KILOMETERS but not PCBs—is slowly breaking down. The Isobaths are in meters 70 RI report used new fish data to recalculate 80 100 200 300 the risk to human health posed by the site 500 400 600 700 and found that fish, especially bottom-feed 800 ers like white croaker, still contain levels of Point Conception DDT and PCBs that warrant fish advisories Los Angeles (see Table 1, Pg. 7). The site still poses a Southern Site threat to wildlife in the area as well, although California Bight San Diego Figure 1: Palos Verdes we have seen some indications of recovery, Southern California Superfund like bald eagles nesting on the Channel Is Study Area lands. ES102006019SCO335398.RR.01 PVS_009.ai 12/06 EPA has been addressing the immediate threat to human is a small but prominent land mass extending into the South health by working with state and local agencies as well as ern California Bight. It is bordered by Santa Monica Bay to community groups to reduce consumption of fish species the north and the San Pedro Shelf to the south. The Chan most likely to contain high concentrations of contaminants. nel Islands lie to the west and northwest. The narrow un The Institutional Controls program is described on Page 4. derwater shelf off the Palos Verdes Peninsula is called the Concurrently, EPA began the Superfund process of investi Palos Verdes Shelf. It is approximately 9 miles long and gation, risk assessment, and remedy selection. less than 1½ miles wide. The seabed over most of the shelf slopes at a gentle 1 to 3 degrees. The shelf breaks at a This fact sheet summarizes EPA’s Remedial Investigation depth of 250 to 300 feet, then drops steeply over 2,300 feet (RI) Report that presents our current understanding of con to the ocean floor. (See Figure 1.) ditions in the Palos Verdes Shelf Study Area. The full RI Report for the Palos Verdes Shelf Superfund Site is avail A 1933 study of the Palos Verdes Shelf characterized it as able online at EPA’s Region 9 website: an area of rocky outcrops and kelp beds. Since then, ur www.epa.gov/region09/waste/sfund/pvshelf. banization, the Portuguese Bend Landslide, and the White Point outfalls have changed that. From the 1930s through Following the RI, EPA will formulate potential remedies to the 1980s, the White Point outfalls have discharged onto the reduce the risk to human health and the environment posed shelf about 4 million tons of sediment. North of the outfalls, by the site. These alternative remedial actions will be de the Portuguese Bend Landslide has contributed an esti scribed in a Feasibility Study, scheduled to be released for mated 6 to 9 million tons of sediment onto the shelf since public review in Fall 2008. EPA will describe its preferred the 1950s. Engineering measures have stabilized the land alternative in a proposed plan that will be available for com slide; nevertheless, the toe of the landslide continues to ment at public meetings in the San Pedro/Palos Verdes erode and act as a source of sediment. Peninsula vicinity. The current and wave patterns along the Palos Verdes Site Characteristics Shelf vary by season and location. Figure 2 shows the general flow patterns for the Southern California Bight. The California coast from Pt. Conception to the Mexican Dominant ocean circulation patterns include the southward- border curves inward, forming a large bay called the flowing California Current, the northward-flowing California “Southern California Bight.” The Palos Verdes Peninsula Countercurrent, and seasonal influences by the northward-trending Davidson Countercurrent. Surface and bottom SANTA BARBARA waters are typically separated in spring through fall by a pycnocline (a zone of rapid change in seawater density) occur ring at depths of 30 to 100 ft. Currents below the pycnocline on the shelf gener 200 Pt Dume ally flow to the northwest, parallel to Santa Monica seabed contours. In contrast, surface 200 currents flow predominantly southeast ward, although they shift to a westerly 200 500 500 flow in late autumn and early winter SAN PEDRO Newport 200 1000 Beach when westerly winds weaken. Most of the time, near-bottom waves and cur 200 rents do not resuspend sediment; how San California Clemente ever, episodically, primarily during 200 Countercurrent 500 500 storms, currents and waves resuspend California 1000 and move sediment across and off the 500 1000 Current 1000 shelf. System 500 1000 W 46048 Figure 2: General flow patterns for the Southern California Bight Page 2 Palos Verdes Shelf Superfund Site February 2008 -100 D -300 -200 D D Redondo Canyon D -7 00 D D D -4 -500 00 -600 D D D PALOSPALOS VERDESVER DES D -80 0 PENINSULAPENINSULA -700 D D PointPoin t VVicentei cente D D D D D D D SURFACE SEDIMENT (0 - 2 CM) D D CONTOURS OF DDTs, 0-200 M WATER - DEPTH (mg/kg DW) D 60 PointPoint D D D FFerminerm in D Sediment Sample Locations D D Outfall s D Outfalls -8 D 00 D 0- 0.05 D D D 0.05- 0.1 0.1- 0.2 -800 D D -1 00 0.2- 0.5 D 0.5- 1 D 1-1.5 800 1.5- 3 - 3-10 D -80 10- 25 ³ 0 D 25- 50 50- 90 90- 155 0 - -80 800 0 1.5 -500 Miles -700 -600 Figure 3 (DDT deposit map): The effluent-affected (EA) deposit is over 2 feet thick and has surface DDT concentrations of 200 ppm (parts Page 3 per million) at the outfalls. As the deposit fans out to the northwest, surface contaminant concentrations drop to 2 to 10 ppm, with concentra tions less than 1 ppm closer to shore and 3 to 15 ppm over the shelf break. Beneath this top layer of 6 to 12 inches, the sediments contain contaminant concentrations in the 100 to 200 ppm range. Why are there tons of DDT and PCBs on Palos Verdes Shelf? Institutional Controls Program Los Angeles County wastewater (effluent) has discharged The Institutional Controls (ICs) program was put at White Point off the Palos Verdes Shelf since 1937. Sew- in place to address the human health risks as age is treated at the Joint Water Pollution Control Plant in sociated with consumption of certain fish, such the City of Carson before it enters the outfalls. The Los as white croaker, caught off the Palos Verdes Angeles County Sanitation District (LACSD) is in charge Peninsula that typically contain high concentra of the county’s sanitation system. Among the many indus- tries that used the sewer system was the Montrose Chemi- tions of DDTs and PCBs. The ICs program has cal Corp., the nation’s largest manufacturer of DDT. From three components: public outreach and educa the 1950s to 1971 tons of DDT and associated manufactur- tion, fish monitoring, and enforcement. The pro ing waste entered the sewer system to be discharged ulti- gram relies on partnerships with other federal, mately from the outfalls at White Point. In 1971, the last state and local agencies and community-based year Montrose used the county sewers, an estimated 50,500 organizations to enforce the commercial catch lbs. of DDT were discharged from the outfalls. PCBs, an- ban and bag limit on white croaker and to edu other persistent hazardous substance, also formed part of cate the public on fishing practices and fish the industrial waste stream that was discharged to the preparation methods that minimize exposure to sewer system until their ban in 1976. After these persistent contaminants. Information about the ICs program pollutants ceased to dominate the waste steam, LACSD can be found online at www.pvsfish.org. continued discharging treated waste onto Palos Verdes Shelf. This created a layer of cleaner sediment on top of the DDT- and PCB-contaminated sediment. On the Palos Verdes Shelf, an estimated 5.7 million tons of sediment have been affected by the effluent discharged from the White Point outfalls.